Abstract: A retarder system for commercial vehicles is provided which consists of a transmission oil circuit (18) for lubrication of the transmission and of a retarder cooling circuit (4) which uses oil as operating fluid, both circuits being coupled via a connection (21) so that in the non-activated braking state of the retarder (1), for increasing the transmission oil flow rate through a radiator (3), oil can be branched off from the transmission oil circuit (18). In addition a retarder pump (12) is proposed which has a prime mover (25), preferably an electrical motor.